1. Field of the Invention
Example embodiments of the present invention relate to a method of driving a light source, a light source apparatus for performing the method, and a display apparatus having the light source apparatus. More particularly, example embodiments of the present invention relate to a method of driving a light source for removing noise, a light source apparatus for performing the method, and a display apparatus having the light source apparatus.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) apparatus includes an LCD panel displaying an image using optical transmittance of liquid crystal molecules and a backlight assembly disposed below the LCD panel to provide the LCD panel with light.
The LCD panel includes an array substrate, a color filter substrate and a liquid crystal layer. The array substrate includes a plurality of pixel electrodes and a plurality of thin-film transistors (TFTs) electrically connected to the pixel electrodes. The color filter substrate faces the array substrate and has a common electrode and a plurality of color filters. The liquid crystal layer is interposed between the array substrate and the color filter substrate. When an electric field generated between the pixel electrode and the common electrode is applied to the liquid crystal layer, the arrangement of liquid crystal molecules of the liquid crystal layer is altered to change the optical transmissivity of the liquid crystal layer, so that an image is displayed on the LCD panel. The LCD panel displays a white image of a high luminance when an optical transmittance is increased to maximum, and the LCD panel displays a black image of a low luminance when the optical transmittance is decreased to minimum.
Recently, a method of local dimming the backlight assembly having a plurality driving blocks has been developed. In the method of local dimming, the driving blocks of the backlight assembly are individually controlled according to the gray scale of an image displayed on the LCD panel. However, there are some problems with the method of local dimming.
Firstly, the driving blocks are repeatedly driven to turn light on and off to cause noise. The noise may increase when the frequency of the noise is higher. Secondly, a TFT of the LCD panel may be affected by the light being turned on and off of the driving blocks to cause waterfall noise. Thirdly, the light source may cause flicker when a driving signal suddenly changes from a high level into a low level to change the current level of the driving signal.
A design of an inverter and a printed circuit board (PCB) has been developed to prevent the flicker. However, the inverter and the PCB have difficulty in preventing the noise and the waterfall noise. The waterfall noise may be prevented when interference between the frequency of the driving signal and a frame frequency is reduced to minimum.
However, the image signal is commonly transmitted by using an NTSC mode, a PAL mode, etc. In the NTSC mode and the PAL mode, the frame frequencies are different from each other, so that the width of a frequency band in which the waterfall noise is not generated is very narrow. Also, the frequency band satisfying the NTSC mode and PAL modes satisfying the frequency band is too high. Thus, the noise may be increased.